Positioning apparatuses are utilized in a variety of applications, such as scanning probe microscopy, micro-scale and nano-scale characterization and testing, and micro-scale and nano-scale fabrication or assembly. In general, a sample resting on a stage is moved approximately into position by a coarse positioning apparatus and then adjusted into a precise position by a precision positioning apparatus having finer resolution. In many cases, positioning apparatuses employ piezoelectric actuators.
Referring to FIG. 1, one example of a positioning apparatus is a friction-driven actuator 100 used for positioning a sample 199 that rests on a driven element 190. A piezoelectric (PZT) element 150 is attached to a base 110. A friction element 170 coupled to the PZT element 150 frictionally engages a bottom surface of the driven element 190. The PZT element 150 elongates or contracts in the X direction in response to an applied electrical signal, causing the friction element 170 to move along the X axis. This linear motion is transferred to the driven element 190 via the frictional engagement between the friction element 170 and the driven element 190, thus causing the driven element 190 to slide relative to the base 110 and effecting Xmotion of the sample 199 in the X direction.